Avocado variety named ‘Uzi’

ABSTRACT

A new and distinct  Persea americana  variety having strong tolerance to  Phytophthora cinnamomi  when used as a rootstock. It is an extremely vigorous and fast-growing rootstock that is capable of supporting a ‘Hass’ tree growing to 15 ft. in 2 years. It&#39;s yields are generally high and consistent. ‘Uzi’ leaves exhibit burn due to salt damage, but this does not seem to affect the growth or yield of the ‘Hass’ variety.

Latin name of the genus and species: The avocado cultivar of thisinvention is botanically identified as Persea americana Mill.

Variety denomination: The variety denomination is ‘Uzi’.

BACKGROUND OF THE INVENTION

Avocado root rot is the limiting factor for the growth of avocadosthroughout the world. Avocado root rot is caused by the fungusPhytophthora cinnamomi, which attacks and kills the feeder roots ofavocado trees. The resultant lack of roots causes the tree to eventuallydie from water stress. There are a number of varieties of rootstocksthat have some tolerance to the disease. These varieties included ‘Duke7’ (unpatented), the most commonly planted tolerant rootstock in theworld; and ‘Thomas’ (U.S. Plant Pat. No. 6,628), another root rottolerant rootstock. However, even with these rootstocks, growers muststill use a variety of methods, including mounding, mulching and theapplications of chemical fungicides, to keep the tress from dying inmany soils. More resistant rootstocks are necessary to eliminate avocadoroot rot as a major disease threat.

Screening and Greenhouse Evaluation of Rootstocks

‘Uzi’ was identified and characterized using the following screeningprotocol. As it is difficult to breed avocados because only one inapproximately one thousand flowers actually set fruit, plant breedingblocks of avocados were isolated to prevent out-crossing withsusceptible rootstocks. The breeding blocks were made up of variouscombinations of selected rootstocks including, ‘Thomas’ (U.S. Plant Pat.No. 6,628), ‘Barr Duke’ (U.S. Plant Pat. No. 6,627), ‘G6’, ‘Duke 7’,‘Duke 9’, ‘UC 2001’, ‘UC 2011’, ‘Toro Canyon’ (U.S. Plant Pat. No.5,642), ‘Spencer’, ‘CR1-71’, ‘G 810’, ‘G 875’, ‘G 755A’, ‘VC 256’, and‘Steyemarkii’. In order to synchronize blooming, attempts were made togirdle late-blooming varieties and spray early-blooming varieties withthe pesticide Unicona-zole-P.

Initial screening was carried out by germinating seeds, which wereharvested from the breeding blocks, in flats of vermiculite in thegreenhouse. Phytophthora cinnamomi-infested millet was placed in rowsalong with the young roots of the test seedlings. After 8-10 weeks rootswere evaluated and those with a high percentage of surviving roots weretransplanted to soil mix incorporated with P. cinnamomi-infested millet.Rootstocks that survived this test were planted and grown in P.cinnamomi-infested soils. Survivors were examined more carefully forvarious types of resistance using asexual propagated material.

-   -   a. Root survival—Rootstocks were grown in typical California        avocado soils, inoculated with P. cinnamomi and evaluated for        growth, root length and percent healthy roots.    -   b. Root regeneration—Rootstocks were grown in soil inoculated        with P. cinnamomi, treated with Aliette to halt Phytophthora        root rot and evaluated for root regeneration.    -   c. Attraction to P. cinnamomi—Roots of the rootstocks were        placed in water baths with motile zoospores of P. cinnamomi. The        numbers of spores attracted to the roots were evaluated.

Rootstocks that performed well in the screening and greenhouseevaluations were further tested under field conditions.

Selection of ‘Uzi’

‘Uzi’ was developed at Riverside, Calif. The maternal parent is ‘G6’(unpatented) avocado variety. The pollen parent is unknown.Specifically, the ‘Uzi’ rootstock variety was selected in 1993 from anagricultural operations land located Riverside, Calif. The fruit werecollected from the avocado breeding blocks, the seed removed, andplanted in vermiculite. The seeds were grown in a greenhouse. The plantswere inoculated with the fungus Phytophthora cinnamomi. After showingtolerance to the disease, ‘Uzi’ was chosen as a single plant for furthertesting. Budwood was collected from the plants and grafted to the stumpsof adult avocado trees that had been cut down at Irvine, Calif. The newvarieties grew into trees which provided budwood for further testing. Atleast two ‘mother’ trees of the variety are growing in Irvine, Calif.,along with the germplasm. During screening and evaluation, ‘Uzi’, whichwas selected and originally designated ‘PP14’, distinguished itself fromother varieties, including the maternal parent ‘G6,’ by having a hightolerance against Phytophthora root rot. The properties of ‘Uzi’ werefound to be true to type and transmissible by asexual reproduction.

BRIEF SUMMARY OF THE INVENTION

This invention relates to a new and distinct avocado variety. ‘Uzi’ isan avocado tree having a rootstock that has a high tolerance againstPhytophthora root rot. It is an extremely vigorous and fast-growingrootstock that is capable of supporting a ‘Hass’ tree growing to 15 ft.in 2 years. It's yields are generally high and consistent. ‘Uzi’ leavesexhibit burn due to salt damage, but this does not seem to affect thegrowth or yield of the ‘Hass’ variety.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a eight-year-old top-worked tree of the ‘Uzi’ varietywhile growing in Irvine, Calif.

FIG. 2 illustrates typical mature foliage of the ‘Uzi’ variety withdimensions in centimeters shown at the bottom.

FIG. 3 illustrates typical flush foliage of the ‘Uzi’ variety withdimensions in centimeters shown at the bottom.

FIG. 4A illustrates typical inflorescence with dimensions in centimetersshown at the right, and FIG. 4B illustrates typical inflorescence byitself.

FIG. 5 illustrates a typical external view of the fruit of the ‘Uzi’variety, with dimensions in centimeters shown at the bottom.

FIG. 6 illustrates typical internal views of the fruit of the ‘Uzi’variety, with and without the seed. Dimensions in centimeters are shownat the bottom.

DETAILED DESCRIPTION OF THE INVENTION

The following is a detailed description of the new ‘Uzi’ variety, whichwas taken from an approximately eight-year-old mature tree, with theexception as a rootstock for a specific scion when reference is made toroot rot resistance and salinity tolerance. The tree is located in anexperimental orchard in Irvine, Calif. and is grafted on a Perseaamericana seedling used as a rootstock.

The Royal Horticultural Society (R.H.S.) color Chart is used herein forthe color description of the rind, seed, bark, leaf, flower, flesh colorand other interest of the ‘Uzi’ avocado tree.

Trees, Foliage, and Flowers

-   Tree:    -   -   Growth habit.—Vigorous, upright and spreading when compared            to the rootstock ‘Thomas’.        -   Vigor.—Below are data on the vigor of ‘Hass’ grafted onto            the rootstock ‘Uzi’, as determined by trunk diameter            measurements from trees planted in an orchard with            Phytophthora cinnamomi in Escondido, Calif.

TABLE 1 Trunk diameter (cm) Rootstock year 1 year 2 year 3 year 4 year 5PP # 14 ‘Uzi’ 2.85 5.14 8.57 10.6 12.54 Thomas 2.44 4.29 6.75 8.40 10.84Escondido Ca., with Hass scion

TABLE 2 Canopy volume (cubic feet) Rootstock year 1 year 2 year 3 year 4year 5 PP # 14 ‘Uzi’. 21.86 163.21 504.3 669 1338.2 Thomas 13.56 84.48388.5 367. 1076.2 Escondido Ca., with Hass scion

-   -   -   Size.—Large. The typical canopy size of a three year old            top-worked ‘Thomas’ is 388 cu.ft. By comparison the canopy            size of a three year old topworked ‘Uzi’ is 504 cu.ft. The            tree is 610-915 cm in height when fully grown at the orchard            site in Irvine, Calif.

-   Branch:    -   -   Color.—The color of the one year old branch is green (RHS            146C).        -   Smoothness.—The bark of a one year old branch is smooth.        -   Lenticels.—The lenticels of a one year old branch are            conspicuous.

-   Main stem:    -   -   Color.—Brown (RHS N 200C and N 200D).        -   Texture of bark.—Corky.

-   Young shoot (flush):    -   -   Intensity of anthocyanin coloration.—Weak.        -   Anthocyanin coloration.—Grayed-orange (RHS 165B).        -   Color.—Grayed-orange (RHS 165B).        -   Conspicuousness of lenticels.—Medium.        -   Color of lenticels.—Grayed-purple (RHS 185A).        -   Size of lenticels.—1.0-3.0 mm long.        -   Concentration of lenticels.—+/−25 lenticels per square cm.        -   Color of upper side.—Grayed-green (RHS 194B).        -   Glossiness of upper side.—Medium.        -   Color of lower surface.—Grayed-green (RHS 193B).

-   Mature leaf:    -   -   Length.—13.0 cm.        -   Width.—5.5 cm.        -   Ratio length/width.—2.4.        -   Shape.—Elliptical.        -   Color of upper side.—Green (RHS 139A).        -   Color of lower side.—Green (RHS 137B).        -   Glossiness of upper side.—Medium-high.        -   Prominence of veins on lower side.—Prominent and in relief.        -   Color of veins.—Yellow-green (RHS 145A).        -   General shape and cross-section.—Flat, slightly concave.        -   Reflexing of apex.—Absent.        -   Color of petiole.—Yellow-green (RHS 144A).        -   Anise aroma.—Present.        -   Margin.—Undulation of margin is weak, and the leaf margin is            entire.        -   Leaf apex shape.—Acute.        -   Leaf base shape.—Elliptical.        -   Length of leaf petiole.—Approximately 2.8 cm.        -   Diameter of leaf petiole.—Approximately 2.0 mm.        -   Leaf arrangement.—upright.

-   Flower:    -   -   Bud size.—Approximately 3 mm in length and approximately 2.5            mm in diameter.        -   Bud shape.—Ovoid.        -   Bud color.—Grayed-green (RHS 197C).        -   Opening.—Belongs to group “B”, female opening (i.e. with            mature pistil) occurs in the afternoon, the flower closes            over night, and the male opening (i.e. with mature stamens)            occurs the next morning; the flower's opening cycle lasts            20-24 hours.        -   Petals.—Borne in two whorls of three perianth lobes. The            petals possess entire margins and petal coloration is near            yellow-green (RHS 151D). Both the upper and lower petal            surfaces are near yellow-green (RHS 151D).        -   Stamen.—There are commonly nine fertile stamens with each            having two basal nectar glands that are grayed-orange (RHS            174A) in color and three staminodla. The anthers are            tetrathecal.        -   Pistil.—The single pistil with a slender style and small            stigmatic surface has one carpel with one ovule. The ovary            is superior.        -   Sepals.—There are 6 sepals which are approximately 5 mm in            length and approximately 3 mm in width, and the color of            both sepal surfaces is yellow-green (RHS 151A).        -   Pedicel.—Commonly approximately 6 mm in length and            approximately 2.0 mm in diameter. The coloration is near            yellow-green (RHS 151B).        -   Peduncles.—Approximately 5.7 cm in length and approximately            3.0 mm in diameter. The coloration is yellow-green (RHS            151A).        -   Number of flowers on inflorescence.—Approximately 108-135            flowers per inflorescence.        -   Fragrance.—Absent.        -   Bloom.—Bloom period at Riverside, Calif. experiment station            varies with cultural conditions. On average ‘Uzi’ has been            found to bloom from 25^(th) of January through the 15^(th)            of March.

Fruit, Fruit and Production Characteristics

-   Fruit:    -   -   Length.13 7.0 cm.        -   Width.—5.5 cm.        -   Ratio length/width.—1.3.        -   Weight.—53.4 grams.        -   Shape.—Narrowly obovate, with an apex diameter of            approximately 2.2 cm and a base diameter of approximately            3.9 cm at the widest point.        -   Color of skin (when ripe).—Grayed-purple (RHS N186).        -   Texture of skin.—Smooth.        -   Presence of longitudinal ridges.—Absent.        -   Thickness of skin.—Thin.        -   Adherence of skin to flesh.—Weak.        -   Main color of flesh.—Yellow-green (RHS 144B).        -   Color of intensely colored area of flesh next to            skin.—Yellow-green (RHS 144A).        -   Width of intensely colored area next to skin.—1.0 mm.        -   Conspicuousness of fibers in flesh.—Conspicuous.-   Seed:    -   -   Length.—4.7 cm.        -   Width.—4.0 cm.        -   Weight.—11.9 grams.        -   Shape (in longitudinal section).—Circular.        -   Shape (in cross section).—Circular.        -   Color of seed coat (fresh).—Grayed-orange (RHS 177A).        -   Cotyledon color.—Orange-white (RHS 159B).        -   Time of harvesting.—‘Uzi’ fruit ripen in September/October            (in Riverside Calif.).        -   Resistance to pests.—Strong resistance to Phytophthora            cinnamomi.        -   Tolerance to salinity.—Medium.        -   Market use.—The fruit of ‘Uzi’ are not intended for market            use, but rather the variety is used as a rootstock onto            which commercial varieties, such as ‘Hass’ are grafted.

TABLE 3 Rootstock rating at Santana, Ventura County, August 2001¹ Treerating Canopy Trunk No. trees Rootstock (0-5; 5 = dead) volume (cu ft)diameter (cm) dead ‘Steddom’ 0.80 a 13.89 a 1.92 a 1 ‘Merensky II’ 0.90a 15.10 a 1.48 a 1 ‘Uzi’ 0.90 a 16.92 a 2.02 a 0 ‘Zentmyer’ 1.05 a 16.48a 2.05 a 1 ‘G755A 1.65 a  5.55 a 1.62 a 1 (Brokaw)’ ‘Medina’ 1.90 a12.66 a 1.70 a 2 ‘Berg’ 2.20 a 13.80 a 1.29 a 4 ‘McKee’ 2.35 a  9.05 a1.52 a 1 ‘Duke 7’ 2.50 a 11.40 a 1.24 a 4 ‘Thomas’ 2.65 a 10.22 a 1.15 a4 ‘G755 A 2.75 a 11.66 a 1.49 a 2 (C&M)’ ‘UC 2023’ 3.00 a  6.21 a 1.25 a3 ¹Mean values in each column followed by identical letters are notstatistically different according to Waller's k-ratio t test.

TABLE 4 Rootstock rating at Santana, Ventura County, November 2002.Two-year trial to-date. Tree rating Canopy Trunk Fruit rating ‘Root-(0-5; volume diameter (0-5; stock’ 5 = dead) (cu ft) (cm) 5 = heavy)‘Merensky 0.17 d 72.27 abc 3.49 ab 0.78 bcd II’ ‘Uzi’ 0.50 cd 69.64 abcd3.64 a 2.50 a ‘Steddom’ 1.00 bcd 67.95 abcd 2.94 abc 1.70 abc ‘Medina’1.06 bcd 79.89 ab 3.26 ab 0.00 d ‘Zentmyer’ 1.50 bcd 81.44 a 3.19 ab0.60 bcd ‘Duke 7’ 1.67 bcd 32.48 abcde 2.31 abcd 1.11 abcd ‘Berg’ 1.72bcd 46.57 abcde 2.21 abcd 2.00 ab ‘McKee’ 1.78 abcd 30.92 bcde 2.24 abcd0.22 cd ‘G755A 2.30 abcd 19.98 de 1.90 bcd 0.10 d (Brokaw)’ ‘Thomas’2.60 abc 31.50 bcde 2.02 abcd 0.30 cd ‘UC 2023’ 2.95 ab 25.50 cde 1.41cd 0.20 d ‘G755A 4.00 a 15.71 e 0.82 d 0.00 d. (C&M)’ Tip burn ratingCanker rating No. trees Rootstock (0-5) (0-5) dead ‘Merensky II’ 0.00 a0.33 a 0/9  ‘Uzi’ 0.33 a 0.00 a 1/10 ‘Steddom’ 0.25 a 0.00 a 2/10‘Medina’ 0.75 a 0.00 a 1/9  ‘Zentmyer’ 0.38 a 0.63 a 1/10 ‘Duke 7’ 0.38a 0.38 a 3/9  ‘Berg’ 0.17 a 0.83 a 3/9  ‘McKee’ 0.43 a 0.29 a 2/10‘G755A (Brokaw)’ 0.29 a 0.14 a 3/10 ‘Thomas’ 0.17 a 1.00 a 4/10 ‘UC2023’ 0.00 a 0.00 a 5/10 ‘G755A (C&M)’ — — 8/10

TABLE 5 Rootstock ratings of avocado trees planted in root rot soil atEscondido, July 2002 Tree rating Canopy Trunk Fruit set 0-5; volumediameter rating 0-5; Rootstocks 5 = dead Cu ft Cm 5 = heavy ‘Zentmyer’0.00 c 397.4 abc 7.12 bcd 1.53 cd ‘Rio Frio’ 0.00 c 313.5 cdef 6.33 cdef2.13 bcd ‘Merens I’ 0.00 c 543.6 a 8.74 a 3.50 a ‘Merensk II’ 0.02 c409.0 abc 7.81 abc 2.84 ab ‘VC 241’ 0.06 c 238.4 defg 6.19 defg 1.41 cd‘Uzi’ 0.29 bc 504.3 ab 8.57 ab 2.76 ab ‘Steddom’ 0.36 bc 376.1 bcde 7.07bcd 2.43 bc ‘Thomas’ 0.44 bc 388.5 bcd 6.75 cde 1.12 de ‘Guillemet’ 0.59bc 192.0 fgh 4.90 fgh 1.12 de ‘Spencer 0.63 bc 225.8 efg 5.24 efgh 1.56cd sdlg’ ‘Leo’ 0.67 bc 288.2 cdef 5.89 defgh 1.60 cd ‘Spencer 0.69 bc163.8 fgh 4.65 gh 1.54 cd clonal’ ‘Duke 7’ 1.00 b 129.3 gh 4.38 h 1.47cd ‘G755A’ 0.16 b 294.1 cdef 5.86 defgh 1.56 cd ‘PolyN’ 4.12 a 65.6 h1.26 i 0.24 e Tip Burn Cankers Dead Rootstocks Number trees affected‘Zentmyer’ 0 0 0/15 ‘Rio Frio’ 0 0 0/16 ‘Merens I’ 0 0 0/14 ‘Merensk II’0 1 0/17 ‘VC 241’ 0 0 0/16 ‘Uzi’ 2 0 1/17 ‘Steddom’ 0 0 1/14 ‘Thomas’ 00 1/17 ‘Guillemet’ 3 1 2/17 ‘Spencer sdlg’ 0 0 2/16 ‘Leo’ 0 0 2/15‘Spencer clonal’ 0 0 5/16 ‘Duke 7’ 0 0 3/15 ‘G755A’ 2 1 3/16 ‘PolyN’ 0 014/17 

TABLE 6 rootstock trial tree ratio April 2003¹. Four-year trial to-dateTree rating Canopy volume Trunk diam. Rootstock (0-5; 5 = dead) (cu ft)(cm) Salt ‘MerenI’ 0.00d 551ab  10.7a 0.08cd ‘VC241’ 0.06d 281efgh8.0abc 0.03cd ‘Rio Frio’ 0.07d 362efcd 8.7abc 0.00d ‘Zentmyer’ 0.07d 410bcde 9.2ab 0.32bc ‘MerenII’ 0.18d 532abc  9.4ab 0.21dc ‘Spen sdlg’0.36d 263efgh 6.9bc 0.00d ‘Uzi’ 0.38d 669a   10.6a 0.68a ‘Steddom’ 0.39d478bcd  8.6abc 0.32bc ‘Thomas’ 0.47cd 367cdef 8.4abc 0.62ab ‘Leo’0.77cbd 274efgh 7.3abc 0.13cd ‘Guillemet’ 0.83cbd 190ghi  6.2bc 0.13cd‘Duke7’ 1.34cb 127hi  8.8abc 0.16cd ‘Spen cl’ 1.44b 211fghi  5.3c 0.12cd‘G755A’ 1.69b 322defg 7.0bc 0.25cd ‘PolyN’ 4.15a 77i  1.5d 0.06cd CankerFruit Dead trees Rootstock (0-5; 5 = heavy) rating² (%) ‘MerenI’ 0a2.97abc 0 ‘VC241’ 0a 3.41ab 0 ‘Rio Frio’ 0a 3.73a 0 ‘Zentmyer’ 0a 3.71a0 ‘MerenII’   0.1a 2.97abc 0 ‘Spen sdlg’ 0a 3.57ab 7 ‘Uzi’ 0a 3.47ab 6‘Steddom’ 0a 3.75a 7 ‘Thomas’ 0a 3.53ab 6 ‘Leo’ 0a 3.29ab 13 ‘Guillemet’0a 2.90abc 13 ‘Duke7’ 0a 1.53de 19 ‘Spen cl’ 0a 2.35bcd 23 ‘G755A’ 0a1.78cd 25 ‘PolyN’ 0a 0.29e 82 ¹Mean values in each column followed byidentical letters are not statistically different according to Waller'sk-ratio t test. ²Fruit was rated in November 2003.

TABLE 7 Temecula, yield 2003^(1;2). Four year trial to-date. Fruitweight/ Number Fruit Rootstock tree (kg) fruit/tree weight (kg)‘Zentmyer’ 15.89a 68.64a 0.219a ‘Uzi’ 13.99ab 59.24ab 0.195ab ‘Spencerseedling’ 12.52ab 56.27ab 0.181ab ‘Merensky II’ 11.83ab 51.12ab 0.185ab‘Rio Frio’ 10.87abc 51.33ab 0.187ab ‘Steddom’ 10.01abc 46.20abc 0.175abc‘Thomas’ 8.50abcd 40.12abcd 0.154abc ‘G755A’ 8.08abcd 34.56abcd 0.116bc‘VC241’ 7.44bcd 31.75bcd 0.202ab ‘Guillemet’ 7.42bcd 30.00bcd 0.196ab‘Spencer clonal’ 6.99bcd 32.00bcd 0.136abc ‘Merensky I’ 6.95bcd 32.08bcd0.148abc ‘Leo’ 6.53bcd 28.14bcd 0.140abc ‘Duke 7’ 3.33cd 14.81cd0.138abc ‘PolyN’ 1.72d 5.71d 0.076c ¹Mean values in each column followedby identical letters are not statistically different according toWaller's k-ratio t test. ²Only fruit which were grade size were picked;remaining fruit on trees to be picked later.

TABLE 8 Escondido, Tree ratings, July 2002 Tree No. rating Canopy TrunkNo. trees (0-5; vol. diam trees w/tip No. trees Rootstock 5 = dead) (cuft) (cm) Dead burn w/canker ‘Uzi’ 0.039 b 34.69 a 2.43 a 0 6 0‘Guillemet’ 0.042 b 22.86 a 2.06 a 0 4 0 ‘Zentmyer’ 0.077 b 22.40 a 2.25a 0 2 0 ‘Spencer sdlg’ 0.536 b 27.81 a 2.01 a 0 2 1 ‘Steddom’ 0.615 b18.93 a 1.99 a 1 0 0 ‘Berg’ 0.714 b 21.42 a 1.98 a 0 1 2 ‘Merensky II’0.750 b 32.07 a 2.10 a 2 0 1 ‘Elinor’ 0.786 b 29.44 a 2.03 a 1 0 2‘Thomas’ 0.846 b 23.07 a 1.85 a 1 2 0 ‘Pond’  1.00 ab 30.55 a 2.15 a 1 02 ‘Crowley’  1.083 ab 23.78 a 1.86 a 2 1 0 ‘G755A’  1.231 ab 22.64 a1.85 a 2 0 0 ‘Duke 9’ 2.270 a  9.40 a 1.07 b 5 0 0 There weresignificant differences at P = 0.01 between blocks for all treeparameters analyzed.

TABLE 9 tree ratings, April 2003. Two-year trial to-date. Tree ratingCanopy Trunk Fruit rating (0-5; vol diam (0-5; 5 = Rootstock 5 = dead)(cu ft) (cm) heavy) ‘Uzi’ 0.267 c  88.76 a 4.193 a  0.0 a ‘Berg’ 0.531c  44.16 a 2.956 bc 0.0 a ‘Zentmyer’ 0.600 c  54.37 a 3.393 ab 0.0 a‘Merensky II’ 0.833 bc 68.49 a 3.333 ab 0.0 a ‘Steddom’ 0.867 bc 56.42 a3.127 ab 0.0 a ‘Pond’ 0.906 bc 55.05 a 3.188 ab 0.0 a ‘Spenser sdlg’0.906 bc 51.45 a 2.988 bc 0.0 a ‘Crowley’ 0.964 bc 42.05 a 3.021 bc 0.0a ‘Thomas’ 1.071 bc 49.99 a 2.900 bc 0.0 a ‘Guillemet’  0.167 abc 43.64a 2.960 bc 0.1 a ‘Elinor’  1.393 abc 58.40 a 2.864 bc 0.0 a ‘G755A’2.156 ab 44.21 a 2.819 bc 0.0 a ‘Duke 9’ 2.577 a  32.16 a 1.885 c  0.0 aSalt rating Canker rating No. trees Rootstock (0-5; 5 = severe) (0-5; 5= severe) Dead (%) ‘Uzi’ 0.933 ab  0.000 a 0 ‘Berg’  0.633 abcd 0.000 a6 ‘Zentmyer’ 1.000 a  0.000 a 7 ‘Merensky II’ 0.154 cd  0.308 a 13‘Steddom’ 0.321 bcd 0.286 a 7 ‘Pond’ 0.767 abc 0.200 a 6 ‘Spenser sdlg’0.300 bcd 0.200 a 6 ‘Crowley’ 0.083 d  0.000 a 14 ‘Thomas’ 0.731 abc0.000 a 0 ‘Guillemet’  0.615 abcd 0.133 a 13 ‘Elinor’ 0.333 bcd 0.167 a14 ‘G755A’ 0.846 ab  0.077 a 13 ‘Duke 9’ 0.313 bcd 0.500 a 38

TABLE 10 Temecula rootstock ratings, Sept 2002 Tree rating Canopy TrunkFruit rating (0-5; vol. diam (0-5; Rootstock 5 = dead) (cu ft) (cm) 5 =heavy) ‘Zentmyer’ 0.400 c  40.70 ab 2.79 a 0.00 b ‘Crowley’ 0.618 c 40.38 ab 2.86 a 0.00 b ‘Elinor’ 0.824 c  40.52 ab 2.54 a 0.00 b‘Guillemet’ 0.882 bc 39.13 ab 2.42 a 0.00 b ‘Steddom’ 0.969 bc 29.20 bc 2.13 ab 1.16 a ‘Thomas’ 0.969 bc 31.46 bc  2.13 ab 0.00 b ‘Pond’ 1.088bc 54.08 a  2.78 a 0.00 b ‘Uzi’ 1.188 bc 35.08 ab 2.56 a 0.00 b ‘G755A’2.088 ab 37.85 ab 2.41 a 0.00 b ‘Spencer sdlg’ 2.906 a  11.96 c  1.39 b0.00 b Salt damage Cankers No. trees Rootstock (0-5; 5 = heavy) (0-5; 5= heavy) dead ‘Zentmyer’ 1.50 ab 0.00 a 0/15 ‘Crowley’ 1.34 b  0.00 a1/17 ‘Elinor’ 1.59 ab 0.00 a 1/17 ‘Guillemet’ 1.41 b  0.00 a 2/17‘Steddom’ 1.54 ab 0.50 a 2/16 ‘Thomas’ 1.50 ab 0.00 a 3/16 ‘Pond’ 1.40b  0.00 a 2/17 ‘Uzi’ 1.64 ab 0.00 a 2/16 ‘G755A’ 2.50 ab 0.36 a 4/17‘Spencer sdlg’ 2.63 a  0.00 a 4/16

TABLE 11 Temecula, rootstock ratings, December 2003. Two-year trialto-date Canopy Trunk Fruit rating Tree rating vol diam (0-5; 5 =Rootstock (0-5; 5 = dead) (cu ft) (cm) heavy) ‘Zentmyer’ 0.313c 207.27a6.23a 2.063a ‘Pond’ 0.906c 307.04a 5.75a 1.813a ‘Elinor’ 0.912c 170.37a 4.80a. 1.059a ‘Guillemet’ 1.059c 199.37a 5.73a 0.882a ‘Uzi’ 1.094bc206.04a 4.35a 0.813a ‘Crowley’ 1.250bc 144.14a 5.04a 1.438a ‘Steddom’1.281bc 254.94a 4.89a 1.188a ‘Thomas’ 1.313be 226.39a 5.16a 1.375a‘G755A’ 2.438ab 175.55a 5.23a 0.625a ‘Spencer sdlg’ 2.813a 42.12a 2.26a0.519a Salt damage Cankers Trees Rootstock (0-5; 5 = heavy) (0-5; 5 =heavy) dead (%) ‘Zentmyer’ 1.188ab 0.000a 0 ‘Pond’ 0.321cd 0.000a 13‘Elinor’ 0.469cd 0.000a 6 ‘Guillemet’ 0.893abc 0.000a 18 ‘Uzi’ 0.769abcd0.000a 19 ‘Crowley’ 0.731abcd 0.000a 19 ‘Steddom’ 0.167d 0.000a 25‘Thomas’ 1.308a 0.000a 19 ‘G755A’ 1.167ab 0.000a 25 ‘Spencer sdlg’0.500bcd 0.000a 44

What is claimed is:
 1. A new and distinct rootstock variety of avocadotree having the characteristics substantially as described andillustrated herein.